Existing plastic urinary bags, worn on the thigh or calf, are typically of a design that has remained largely unchanged since such bags were first introduced. An exemplary bag is constructed of two pieces of identically sized and shaped plastic film that is sealed in such a manner as to create a rectangular, flat vessel with an inlet valve at the top and an outlet valve at the bottom. The valves are sealed in place between the two layers of plastic film. To attach the bag to the user's thigh or calf, slits are made at the four corners of the bag to permit the insertion of an adjustable strap (both top and bottom). This strap is usually made of latex rubber or some similar material to which a plastic “button” has been attached. Holes on the strap permit the user to adjust the tension of the strap by stretching the appropriate hole over the button, thus establishing a fixed degree of tension corresponding to the circumference of the leg to which the bag is attached.
Because of the design of such bag, when it is filled with urine it expands to form a rectangular balloon with the surface area of the bag in contact with the leg decreasing steadily in proportion to the volume of liquid contained within the bag. Thus, as the bag fills, it expands in such a manner as to press against the clothing raising the clothing well above the surface of the skin. This tends to make the bag obvious to others, which can be embarrassing to the user. Further, as the bag fills, the force holding the bag in place shifts almost exclusively to the straps, which accentuates the pressure already exerted by the buttons against the user's skin, to cause sores.
In addition, because such bag is constructed of identically sized and shaped sheets of plastic, reuse of the bag after emptying becomes problematic when the two wet surfaces come in contact with one another. The surface tension of the liquid tends to cause the two sides of the bag to stick together, even despite some surface texturing found in some bags. The force required to separate the two sides, which is required to allow the bag to be filled, is sometimes greater than the force exerted by the flow of urine into the bag. Thus, the tendency for the sides to stick together can cause the flow of urine into the bag to be stopped completely with potentially serious health consequences. For those with external catheters, this result can alternatively lead to failure of the catheter itself, which will result in the urine flowing freely onto the leg, clothing, and chair.
Current inlet valves used to prevent backflow add to this problem as well. When the sides of the bag stick together at the top of the bag, they impinge upon the valve because the valve extends into the bag itself. The force required to open the valve therefore includes the force required to open the inlet valve itself and to separate the bag sides from the valve opening. For example, a flat flutter valve that extends into the bag can be affected by pressure exerted against it by the closed sides of the bag. These sides often impinge upon the valve, which interferes with, and sometimes blocks, the flow of urine into the bag. Impingement on these valves also occurs to hinder urine flow when any object is placed on top of the bag, including the user's arms or hands when the bag is worn on the user's thigh.
Current inlet tubes also hinder the flow of urine by causing misalignment between the bag and the catheter that carries the urine. The placement of inlet tubes on existing bags is along the central axis of the bag such that placement of the bag on the user's thigh causes the inlet tubes to point away from the point at which the catheter is inserted or attached to the user. The resulting misalignment often causes the catheter to become constricted as a result of a very small radius bend that forms where the catheter enters the inlet tube. This constriction, like the aforementioned side wall sticking and valve impingement, can interfere with and sometimes block the flow of urine into the bag, which leads to serious health consequences.